class MetricAggregator

final class MetricAggregator implements MetricAggregatorInterface {
    
    /** @var array<AttributesInterface> */
    private array $attributes = [];
    private array $summaries = [];
    public function __construct(?AttributeProcessorInterface $attributeProcessor, AggregationInterface $aggregation, ?ExemplarReservoirInterface $exemplarReservoir = null) {
    }
    public function record(float|int $value, AttributesInterface $attributes, ContextInterface $context, int $timestamp) : void {
        $filteredAttributes = $this->attributeProcessor !== null ? $this->attributeProcessor
            ->process($attributes, $context) : $attributes;
        $raw = $filteredAttributes->toArray();
        $index = $raw !== [] ? serialize($raw) : 0;
        $this->attributes[$index] ??= $filteredAttributes;
        $this->aggregation
            ->record($this->summaries[$index] ??= $this->aggregation
            ->initialize(), $value, $attributes, $context, $timestamp);
        if ($this->exemplarReservoir !== null) {
            $this->exemplarReservoir
                ->offer($index, $value, $attributes, $context, $timestamp);
        }
    }
    public function collect(int $timestamp) : Metric {
        $exemplars = $this->exemplarReservoir ? $this->exemplarReservoir
            ->collect($this->attributes) : [];
        $metric = new Metric($this->attributes, $this->summaries, $timestamp, $exemplars);
        $this->attributes = [];
        $this->summaries = [];
        return $metric;
    }

}